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[dw1305]

Hi all,

must require only a miniscule amount of it, given algae can grow in RO water on a window sill in direct sunlight

Dust...🙂
You can't make chlorophyll without N.

You can store RO indefinitely. It will grow a small fuzz of green algae if it is more than about 5 microS.

Yes, @oreo57 is right, you need <"all fourteen"> of the essential mineral nutrients for plant growth, but some of them <"must be in minute amounts">.

cheers Darrel

 

[dw1305]

Hi all,

Hi Everyone,

In order to kill off algae spores in the water column, the use of UV-C sterilization is worth considering. I used this as part of my battle against cyanobacteria when I discussed it here in post #58:

Cyanobacteria Identification - At Last!

It’s believed to be erythromycin Hi @becks In that case, my understanding is that it wouldn't be considered legal in the UK as it's an antibiotic. JPC

www.ukaps.org

JPC

One for you I think @jaypeecee? <"Ultrasonic irradiation for blue-green algae control">. I have no idea what it does to higher plants.

cheers Darrel

 

[Wookii]

Hi all,

One for you I think @jaypeecee? <"Ultrasonic irradiation for blue-green algae control">. I have no idea what it does to higher plants.

cheers Darrel

Interesting stuff - it's quite surprising that the required frequency is so close to that human auditory band. I would have thought a much high frequency would have been required. Even more surprising was the comment:

Ultrasonic devices are already applied to ponds, pools, lakes and reservoirs to destroy algae and control their growth in an environmentally friendly way.

 

[dw1305]

Hi all,

Even more surprising was the comment: "Ultrasonic devices are already applied to ponds, pools, lakes and reservoirs to destroy algae and control their growth in an environmentally friendly way".

They are a Dutch Company and I think it is used a lot more in Continental Europe. I had a feeling that it had been used somewhere locally to me, possibly this one <"by Bournemouth Water">.

This is the <"link for AL50">.

cheers Darrel

 

[Wookii]

Hi all,

They are a Dutch Company and I think it is used a lot more in Continental Europe. I had a feeling that it had been used somewhere locally to me, possibly this one <"by Bournemouth Water">.

This is the <"link for AL50">.

cheers Darrel

They even have an 'aquaria' version:

AL 5 - Ultrasonic unit

New and environmental friendly technique that helps to keep clean aquaria or small ponds

www.lenntech.com

 

[Wookii]

Some interesting info and microscope images here: https://dreamsails.co/shop/wp-content/uploads/Ultrasonic-Algae-Control.pdf

I can't find much info on the effect on other plants and mosses etc.

 

[dw1305]

Hi all,

I can't find much info on the effect on other plants and mosses etc.

The pdf says that it doesn't control Chara or Nitella or anything more "planty" then them.

cheers Darrel

 

[Wookii]

Hi all,

The pdf says that it doesn't control Chara or Nitella or anything more "planty" then them.

cheers Darrel

I assume that would suggest that mosses and liverworts etc are safe then?

I have dropped Lenntech an e-mail to ask the question directly - and also to find out how much that AL5 unit is! I can't imagine its going to be cheap though!

I am surprised that given this is appears to be a technology in fairly widespread use commercially, to find almost no mention of it in aquariums - other than Tom Barr rubbishing it on the PlantedTank back in 2010.

Ultrasonic algae control?

www.plantedtank.net

 

[jaypeecee]

Hi @oreo57 & Everyone,

This is the bit that I'm homing in on:

"The only nutrient that "causes" algae is ammonia because it allows the spores to become adults".

Forgive me if I've missed something in scanning the most recent posts but is the above statement correct and, if so, what evidence do we have for this? And, sorry to be pedantic, but I assume we'd be talking about ammonium, not free ammonia? This is relevant as we might expect algae to be less prevalent in alkaline water (the NH4+/NH3/pH curve). I hope I'm making myself clear. If not, I'll try again after my morning coffee!

Until then...

JPC

 

[dw1305]

Hi all,

but I assume we'd be talking about ammonium, not free ammonia? ......
This is relevant as we might expect algae to be less prevalent in alkaline water (the NH4+/NH3/pH curve).

You definitely tend to get more green algae in alkaline conditions in the "wild".

cheers Darrel

 

[jaypeecee]

You definitely tend to get more green algae in alkaline conditions in the "wild".

Hi @dw1305

So, that's interesting, isn't it? Doesn't that tend to suggest that algae spores can also get nitrogen from nitrite and nitrate? In other words, algae spores may not be solely dependent on ammonia/ammonium as a source of nitrogen. Perhaps algae spores can also use urea? I wouldn't know.

JPC

 

[jaypeecee]

One for you I think @jaypeecee? <"Ultrasonic irradiation for blue-green algae control">.

Hi @dw1305

It seems that water companies have been investigating this for the last few years:

https://www.acoustics.asn.au/conference_proceedings/INTERNOISE2014/papers/p670.pdf

It's sometimes difficult to think of this as ultrasound when some of the equipment is operating at 1.7MHz! Imagine that! Perhaps those conducting the experiments found that their teeth fell out!

JPC

 

[dw1305]

Hi all,

Doesn't that tend to suggest that algae spores can also get nitrogen from nitrite and nitrate?

My guess is that, at least some of them, can. It is back to the <"one-legged Irishman"> argument.

Because fixed nitrogen is was both rare, and tends to be patchy, in the natural environment having ammonia/um (NH3/NH4+) as a trigger for growth from a resting spore would make sense. It would allow an organism to exploit these sudden booms and then go back to waiting during the busts.

Perhaps algae spores can also use urea?

Possibly, although that <"urea is going to be scavenged pretty effectively"> and ammonia released.

cheers Darrel

 

[jaypeecee]

I think the problem really lies with the term "algae"...

Hi @dw1305

Green algae (chlorophyta), red algae (rhodophyta) and diatoms would appear to be a good starting point. And here's some bedtime reading:

AlgaeBase :: Listing the World’s Algae

Algaebase :: Listing the World's Algae

www.algaebase.org

JPC

 

[oreo57]

Hi all,

You definitely tend to get more green algae in alkaline conditions in the "wild".

cheers Darrel

Which favors free ammonia over ammonium

Also..

Algae Culture and pH

By Matthew Huber and Katie Blaha-Robinson The pH in water measures how acidic or basic that water is. Anyone who has ever maintained a pool can attest that monitoring pH is incredibly important. This is because pH affects nearly every biologic and chemical process, especially...

algaeresearchsupply.com

 

[not called Bob]

that’s interesting, at those frequencies pinnipeds and cetaceans are monitored and mitigated for when using a HIPAP on survey equipment, most fish don’t seem to upset and hang around the ROV’s especially in-front of a visible light source (as opposed to the lasers)

 

[rebel]

I am surprised that given this is appears to be a technology in fairly widespread use commercially, to find almost no mention of it in aquariums - other than Tom Barr rubbishing it on the PlantedTank back in 2010.

Tom says he tried it and it doesn't work. I reckon someone else should also try it!!! How far would ultrasound frequencies travel in water??

 

[Wookii]

Tom says he tried it and it doesn't work. I reckon someone else should also try it!!!

Agreed. It was 10 years ago, you would hope the tech has evolved a little since then. one of the issues my be the active radius of the devices. The Lenntech ones appear to have a minimum active radius - even the smallest unit has a minimum active radius of one metre, which might exclude most domestic aquariums. There is also the fact the sound is being transmitted in a glass box, and similar to transmitting sound in a small room, there will be a lot of reflection, interaction and cancellation of the soundwaves making the results less predictable - not to mention line of sight issues with hardscape etc.

I would think it certainly warrants further testing though. I can only assume that hasn't happened because its cost prohibitive.

How far would ultrasound frequencies travel in water??

Further than I thought they would. I know that sound waves travel a lot further in water, but high frequencies generally don't travel as far as low frequencies.

It obviously depends on the amplitude output of the device, but the commercial units appears to be able to deal with large lakes with a few transducers. The largest of those Lenntech units is specified as covering a 150 metre radius. The big LGSonic units appear to be able to cover a radius of 500 metres: MPC-Buoy - Complete Algae Control Solution - LG Sonic

 

[rebel]

Maybe the use case could be intermittent; much like how I use UV (only used 3 times ever!).